This invention pertains to novel phosphate derivatives, and to methods of preparation of such compounds. This invention is also concerned with compostions useful in the treatment of hypertension.
It is estimated that approximately fifteen percent (15%) or more of the adult population in the United States is hypertensive, i.e., having blood pressures greater than or equal to about 160/95 mm Hg. Of that population, approximately one-half is unaware of their hypertensive condition. An untreated hypertensive is at great risk of developing disabling or fatal left ventricular failure, myocardial infarction, cerebral hemorrhage or infarction, and renal failure at an early age. Hypertension is generally considered the most important risk factor predisposing to coronary and cerebral atherosclerosis. However, it is believed that effective medical control of hypertension will prevent or forestall all complications associated with hypertension, and will prolong the life of the hypertensive patient.
Drug therapy for hypertension includes use of diuretics, sympathetic depressants (e.g., .alpha.-blockers such as reserpine), vasodilators and finally blockers of sympathetic transmission at the neuroeffector junction (e.g., guanethidine or clonidine).
Among the vasodilators currently employed in hypertension therapy are diazoxide and sodium nitroprusside. Side effects of diazoxide therapy include nausea, vomiting, hyperglycemia and tachycardia. Side effects from sodium nitroprusside therapy include nausea, vomiting, agitation, muscular twitching and cutis anserina if blood pressure is reduced too rapidly. Minoxidil is also often used as a vasodilator in hypertension therapy. However, the side effects of minoxidil include sodium and water retention, and hirsutism. Hydralazine, a mild vasodilator, is also employed. Its side effects include headaches, tachycardia, fluid retention, aggravation of angina, gastrointestinal irritation, lupus-like syndrome, drug fever and psychosis.
Acetyl glyceryl ether phosphocholines have been recognized as having potent biological activity in platelet activation, and in vasoconstriction and vasodilation. See, e.g., U.S. Pat. No. 4,329,302, which issued on May 11, 1982 to Hanahan et al. Such phosphocholines have been identified as both a platelet activation factor (PAF) and an antihypertensive polar renomedullary lipid (APRL). See R. L. Wykle et al., FEBS LETTERS, 141: 29-32 (1982); M. L. Blank et al., BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS, 90: 1194-1200 (1979). Antihypertensive phosphocholines do not occur as pre-formed components in the body; rather, such phosphocholines are synthesized by certain cells. See J. Benveniste et al., INT. ARCHS. ALLERGY APPL. IMMUNN., 66 (Supp. 1): 121-126 (1981); E. E. Muirhead, HYPERTENSION, 2: 444-464 (1980). APRL has been described as being accountable in great measure for the endocrine-type antihypertensive action exerted by the renal medullary and the renomedullary interstitial cells. M. L. Blank et al., ID.